1. Identification of Drug Evidence
Lethal Agents
Identification of Drug Evidence

2. Identification of Drug Evidence
Physical Observation - visual inspection.
Screening/Preliminary Tests - do not positively identify the substance but do sufficiently narrow down the many thousands of possibilities so that more specific tests can later be conducted.
Separation Tests - physically separate elements of the sample.
Confirmatory Tests - confirm the specific identity of the drug.

3. Identification of Drug Evidence
Step 1) Physical Inspection
Looking at the substance will tell you a lot about what kind of drug it might be.
Then you can determine what kind of tests you will use.

4. Identification of Drug Evidence
Step 2) Screening Tests/Spot Tests
Spot tests are simple chemical procedures which uniquely identify a substance. They can be done on small samples, even microscopic samples of matter with no preliminary separation.
However, a positive result is only probable cause to believe the drug is present.

5. Identification of Drug Evidence
In a typical spot test, a drop of chemical reagent is added to a drop of an UNKNOWN mixture.
If the substance in question is present, it
produces a chemical
reaction characterized
by one or more unique
observables -- usually
color change.

6. Common Spot Tests Marquis Test:
brown=positive for amphetamine; purple=positive for opiates
pink=positive for aspirin
yellow=positive for psilocybin
Simon's Test:
blue=positive for methamphetamine

7. Common Spot Tests Scott's Test: blue=positive for cocaine
Duquenois-Levine Test:
purple=positive for marijuana
Van Erk Test:
blue violet=positive for LSD

8. Common Spot Tests Gallic Acid Test: green=positive for MDMA
Dillie Koppanyl Test:
blue violet=positive for barbiturates
Chen's Test:
purple=positive for ephedrine

9. Identification of Drug Evidence
If you got a positive spot test:
Step 3) Now you want to confirm the specific identity.
You may first have to undergo a purification step to separate the drug from other substances.
Usually this involves separation tests such as:
gas chromatography
mass spectroscopy
infrared spectroscopy

10. Confirmation Testing
These separation tests are time consuming and expensive, so they should only be run if completely necessary.
GC MS IR

11. Confirmatory Testing
Microcrystalline Tests involve combining the substance with a specific reagent and observing the unique crystal formation with a microscope.
They are low cost and fast to administer.
Cocaine vs.
Methamphetamine

12. Qualitative vs Quantitative
These tests that identify that a drug is present are Qualitative tests.
If you need to know how much of a drug is present, that would require Quantitative tests.
In some cases, the quantity is important for possession charges.

13. Identification of Drug Evidence
So what if you only have a very minute sample of evidence?
If you don't have enough sample to perform all of the necessary tests, what do you do?
You will have to be very conservative,
Perform non-destructive tests first!